Lighted display devices are, of course, well known. By way of example, statically lighted display devices are commonly used for advertising and other types of signage. Animated lighted display devices also are in common usage, such as in relation to variable advertising mechanisms and the like.
Many devices of the prior art, however, are limited in their application. For example, the glass bulbs required for illumination are relatively delicate and cannot be employed in many types of applications that are likely to be subjected to impacts and vigorous movements. Also, it is recognized to be problematic to employ traditional illumination sources in contoured applications, such as relative to dolls and other toys. Still further, providing bright and uniform lighting—lighting devoid of noticeable hotspots—is at best challenging using traditional bulb illumination sources.
Alternative forms of illumination have been attempted in general illumination applications. For example, it is known that optically transmissive materials, such as glass or polymers, may be used as a light or wave guide to propagate light. A waveguide typically includes at least one surface adapted to receive light from a light source and an optically smooth surface for reflecting light propagating through the guide. Common examples of waveguides include optical fibers traditionally used in the data communication industry and more recently light fibers used for illumination purposes.
The prior art also discloses the extraction of light from an optical waveguide along a length of the guide. For example, U.S. Pat. No. 5,432,876 to Appeldorn et al., which is incorporated herein by reference, discloses an illumination device wherein light injected into an end of a light fiber exits the fiber at a predetermined position or positions along the length of the fiber. Light extraction structures or notches are formed in the core of the light fiber. The extraction structures define first and second reflecting surfaces, which reflect in a radial direction a portion of the light propagating axially through the fiber. The reflected light is directed at an angle that is less than the critical angle necessary for continued propagation along the fiber according to the principle of total internal reflection. As a result, the reflected light is extracted from the fiber in a controlled fashion.
However, it has been noted, for example, in U.S. Pat. No. 6,863,428 to Lundin, which is incorporated herein by reference, that the light extraction in such arrangements tended to be inconsistent in intensity. Accordingly, Lundin sought to provide a light fiber that appears uniform in brightness along its length. Under the disclosed invention, a light guide has a light guide core with an optically smooth surface for propagating light therethrough. A light emitting region, which extends along a portion of the core, includes at least one light extraction structure located along the optically smooth surface of the light guide core. The light extraction structure includes an optically reflective surface extending into the light guide core and is oriented to reflect light at an angle less than a critical angle necessary for light to propagate through the light guide core. A diffuse reflective sheet material is disposed around at least a portion of the light guide to direct at least a portion of the light reflected by the light extraction structure back through the light guide to emit the light through the light emitting region of the optically smooth surface. As taught by Lundin, the illumination structure can have a plurality of spaced light extraction structures, which may be equally or unequally spaced.
Unfortunately, even assuming Lundin to have succeeded in providing lighting of a consistent intensity along the length of a light fiber, the knowledgeable observer will appreciate that structures embodying such developments have been limited in their application. The limited application of such technologies has apparently derived from, among other things, the complexities and expense required for their manufacture and application.
It has also been the long sought after goal of many inventors to provide a toy doll capable of simulating animation, such as speech and eye movement. By way of example, U.S. Pat. No. 4,808,142 to Berliner teaches a motor driven mouth actuator that moves a doll's mouth between open and closed positions. In U.S. Pat. No. 3,841,020, Ryan employs a complex set of levers and actuators to create what is nonetheless a limited range of facial expressions. Further still, with U.S. Pat. No. 6,352,464, Madland et al. describe a facial control system where two lip chains are embedded behind two lips.
Most such dolls, however, have proven to lack realism. These prior art dolls have been unable in many cases to achieve a full range of human-like and recognizable facial expressions. Furthermore, many of these prior art dolls have required complex mechanical drive arrangements so that they have been prone to failure. Additionally, the relatively complicated dolls of the prior art have been relatively expensive in manufacture and sale. As a result, many animated dolls of the prior art have been poorly received by the consuming public and have been unable to achieve the widespread application necessary for substantial market success.